U.S. patent application number 10/928285 was filed with the patent office on 2005-11-17 for power management system.
Invention is credited to Chen, Jiwei, Kobildjanov, Oleg, Popescu-Stanesti, Vlad Mihail.
Application Number | 20050253560 10/928285 |
Document ID | / |
Family ID | 37703395 |
Filed Date | 2005-11-17 |
United States Patent
Application |
20050253560 |
Kind Code |
A1 |
Popescu-Stanesti, Vlad Mihail ;
et al. |
November 17, 2005 |
Power management system
Abstract
A method according to one embodiment may include selecting at
least one power supply, among a plurality of different power
supplies, and coupling at least one available power supply to a
load. The method may also include selecting at least one charging
mode, among a plurality of different charging modes, to charge a
rechargeable battery. Of course, many alternatives, variations, and
modifications are possible without departing from this
embodiment.
Inventors: |
Popescu-Stanesti, Vlad Mihail;
(San Jose, CA) ; Chen, Jiwei; (Santa Clara,
CA) ; Kobildjanov, Oleg; (San Jose, CA) |
Correspondence
Address: |
WAGNER, MURABITO & HAO, LLP
TWO NORTH MARKET STREET, THIRD FLOOR
SAN JOSE
CA
95113
US
|
Family ID: |
37703395 |
Appl. No.: |
10/928285 |
Filed: |
August 27, 2004 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
60571176 |
May 14, 2004 |
|
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Current U.S.
Class: |
320/138 |
Current CPC
Class: |
H02J 7/0068 20130101;
H02J 2207/40 20200101; H02J 1/08 20130101 |
Class at
Publication: |
320/138 |
International
Class: |
H02J 007/00 |
Claims
What is claimed is:
1. An apparatus, comprising: an integrated circuit capable of
selecting at least one power supply, among a plurality of different
power supplies, and coupling at least one available power supply to
a load, said integrated circuit further capable of selecting at
least one charging mode, among a plurality of different charging
modes, to charge a rechargeable battery.
2. The apparatus of claim 1, wherein: said integrated circuit is
further capable of coupling at least one said available power
supply to said load and to said rechargeable battery.
3. The apparatus of claim 1, wherein: said integrated circuit is
further capable of selecting at least one charging phase, among a
plurality of different charging phases, to charge said rechargeable
battery.
4. The apparatus of claim 3, wherein: said plurality of different
charging phases selected from the group consisting of a wake-up
phase, a constant current phase, and a constant voltage phase.
5. The apparatus of claim 1, wherein: said plurality of different
charging modes being selected from the group consisting of a switch
mode and a linear mode.
6. The apparatus of claim 1, wherein: said at least one power
supply comprising a high power supply capable of delivering an
instantaneous power to said load.
7. The apparatus of claim 1, wherein: said at least one power
supply comprising a restricted power supply capable of delivering a
restricted power to said load.
8. The apparatus of claim 1, wherein: said at least one power
supply comprising said rechargeable battery capable of delivering
power to said load.
9. The apparatus of claim 2, wherein: said integrated circuit is
further capable of allocating power to said load and allocating any
remaining power to said rechargeable battery.
10. A method, comprising: selecting at least one power supply,
among a plurality of different power supplies, and coupling at
least one available power supply to a load; and selecting at least
one charging mode, among a plurality of different charging modes,
to charge a rechargeable battery.
11. The method of claim 10, further comprising: coupling at least
one said available power supply to said load and to said
rechargeable battery.
12. The method of claim 10, further comprising: selecting at least
one charging phase, among a plurality of different charging phases,
to charge said rechargeable battery.
13. The method of claim 12, wherein: said plurality of different
charging phases selected from the group consisting of a wake-up
phase, a constant current phase, and a constant voltage phase.
14. The method of claim 10, wherein: said plurality of different
charging modes being selected from the group consisting of a switch
mode and a linear mode.
15. The method of claim 10, wherein: said at least one power supply
comprising a high power supply capable of delivering an
instantaneous power to said load.
16. The method of claim 10, wherein: said at least one power supply
comprising a restricted power supply capable of delivering a
restricted power to said load.
17. The method of claim 10, wherein: said at least one power supply
comprising said rechargeable battery capable of delivering power to
said load.
18. The method of claim 11, further comprising: allocating power to
said load and allocating any remaining power to said rechargeable
battery.
19. A system, comprising: a portable electronic device comprising
an integrated circuit and a load, said integrated circuit capable
of selecting at least one power supply, among a plurality of
different power supplies, and coupling at least one available power
supply to said load, said integrated circuit further capable of
selecting at least one charging mode, among a plurality of
different charging modes, to charge a rechargeable battery.
20. The system claim 19, wherein: said integrated circuit is
further capable of coupling at least one said available power
supply to said load and to said rechargeable battery.
21. The system claim 19, wherein: said integrated circuit is
further capable of selecting at least one charging phase, among a
plurality of different charging phases, to charge said rechargeable
battery.
22. The system claim 21, wherein: said plurality of different
charging phases selected from the group consisting of a wake-up
phase, a constant current phase, and a constant voltage phase.
23. The system claim 19, wherein: said plurality of different
charging modes being selected from the group consisting of a switch
mode and a linear mode.
24. The system claim 19, wherein: said at least one power supply
comprising a high power supply capable of delivering an
instantaneous power to said load.
25. The system claim 19, wherein: said at least one power supply
comprising a restricted power supply capable of delivering a
restricted power to said load.
26. The system claim 19, wherein: said at least one power supply
comprising said rechargeable battery capable of delivering power to
said load.
27. The system claim 20, wherein: said integrated circuit is
further capable of allocating power to said load and allocating any
remaining power to said rechargeable battery.
28. The system of claim 19, wherein: said portable electronic
device is selected from the group consisting of a laptop computer,
a portable phone, a digital still camera and a digital movie
camera.
29. The system of claim 19, wherein: said load comprising at least
one active electronic circuit capable of receiving power from at
least one said power supply.
Description
[0001] This application claims priority to U.S. Provisional
Application Ser. No. 60/571,176, filed May 14, 2004, the teachings
of which are hereby incorporated by reference in their
entirety.
FIELD
[0002] The present disclosure relates to a power management
system.
BACKGROUND
[0003] The boom of portable electronic devices, such as notebook
computers, mobile phones, digital still cameras and camcorders, has
caused an increasing demand for rechargeable batteries, which
include, but are not limited to, nickel-cadmium, nickel-metal
hydride, lithium-ion, lithium-polymer batteries.
[0004] It may be desirable for the portable electronic devices to
be in-field rechargeable, which means that the battery can be
recharged without removing the battery from the devices or
affecting the normal function of the devices. When the external
power source charges the battery and power the system
simultaneously, the charging current should be adjusted
automatically to fulfill first the current requirement of the
system.
[0005] There are two types of charging method. One is switching
mode, where the battery is charged through a periodically on/off
switch. The other one is linear mode, where the battery is charged
through a variable resistor. Switching mode charging has higher
efficiency, but introduces more switching noise into the system due
to the generation and use of an oscillation signal. In contrast,
linear mode charger is cleaner at the cost of higher power
dissipation.
[0006] Different devices may require different charging modes, or
the same devices may require different charging modes under
different conditions. Thus it is desirable to have a dual mode
battery charger for portable electronic devices, and it should be
configurable according to user requirements.
[0007] Different types of rechargeable batteries may require
different charging phases under different conditions. For example,
for deeply discharged battery, a small wake-up charging current may
be required to revive it. For normally discharged battery, a large
charging current may be required to achieve the highest charging
speed. For almost full battery, a tapering charging current may be
required to keep the battery voltage at a constant level.
[0008] If the battery requires a large charging current to maximize
the charging speed, a soft-start function may be desired to prevent
a big inrush current flowing into the battery, which is realized by
gradually increasing the charging current to its full scale.
[0009] A portable electronic device may be powered by multiple
power sources, such as batteries, high power supplies, and
restricted power supplies, which may be perturbed when the drawing
current exceeds the predetermined maximum rating current. The high
power supplies have the highest priority, the restricted power
supplies have a medium priority, and the batteries have the lowest
priority. If one of the high power supplies is present, it should
charge the battery and power the system, regardless the presence of
the restricted power supplies or batteries. If all of the high
power supplies are not available and one of the restricted power
supplies is available, this restricted power supply should be
connected to the system power line using a soft-start procedure to
limit the inrush current below its predetermined maximum rating
current. When an over-current event occurs, the power input of the
system should be switched from the restricted power supply to one
of the batteries. Moreover, during any switching procedure, the
system power integrity should be assured.
BRIEF DESCRIPTION OF THE DRAWINGS
[0010] Features and advantages of embodiments of the claimed
subject matter will become apparent as the following Detailed
Description proceeds, and upon reference to the Drawings, wherein
like numerals depict like parts, and in which:
[0011] FIG. 1 is a diagram illustrating an exemplary system
embodiment;
[0012] FIG. 2 is a diagram illustrating exemplary power management
circuitry;
[0013] FIG. 3 is a diagram illustrating exemplary power path
circuitry;
[0014] FIG. 4 is a diagram illustrating exemplary charger path
circuitry;
[0015] FIG. 5 is a diagram illustrating exemplary charger
controller circuitry;
[0016] FIG. 6 is a diagram illustrating exemplary power source
selector circuitry; and
[0017] FIG. 7 is a flowchart of exemplary operations according to
an embodiment.
[0018] Although the following Detailed Description will proceed
with reference being made to illustrative embodiments, many
alternatives, modifications, and variations thereof will be
apparent to those skilled in the art. Accordingly, it is intended
that the claimed subject matter be viewed broadly, and be defined
only as set forth in the accompanying claims.
DETAILED DESCRIPTION
[0019] FIG. 1 depicts a diagram illustrating an exemplary system
embodiment. The system may comprise a portable electronic device
100 having multiple power inputs 102, 104 and comprising power
management circuitry 106. The portable electronic device 100 may
comprise, for example, a laptop computer, a portable phone, a
digital still camera, a digital movie camera and/or other
electronic device. The device 100 may utilize and/or control a
plurality of different power supplies, for example one or more high
power supplies 102 and/or one or more restricted power supplies
104.
[0020] System 100 may also include one or more rechargeable and/or
non-rechargeable batteries 108, a system load 110, and power
management circuitry 106 capable of managing power between one or
more power supplies, one or more batteries and the system load.
"High power supply", as used herein, may be defined as a power
supply capable of delivering an instantaneous power to a load. For
example, one or more high power supplies 102 may be capable of
providing at least the maximum instantaneous power that may be
required by the system load 110. A specific example of a high power
supply may include an AC adapter or a car adapter. "Restricted
power supply", as used herein, may be defined as a power supply
capable of delivering a restricted power to a load. For example,
one or more restricted power supplies 104 may be capable of
delivering limited power to a load. Other exemplary restrictions
may include a soft hand-shake with the system 100, tight
over-current conditions, and/or timing restrictions. A specific
example of a restricted power supply includes the power line of
universal serial bus (USB) port, which can provide 100 mA current
(for low power USB hub port) or 500 mA current (for high power USB
hub port) and needs a preliminary communication between itself and
the system to set the conditions. Another specific example of a
restricted power supply includes a "Fire-Wire" interface. Although
USB and Fire-Wire may represent examples of a restricted power
supply, it should be understood that the restricted power supply
104 should not be limited only to USB or Fire-Wire ports, but it
should include any existing and/or new and/or emerging interfaces
or power supplies.
[0021] Batteries 108 may comprise any type of battery, for example,
a rechargeable battery comprising nickel-cadmium, nickel-metal
hydride, lithium-ion, and lithium-polymer. These batteries may have
a single cell or multiple cells. The system load 110 may include an
active electronic circuit which consumes current. System load 110
may include one or more discrete components, chips, and/or
electronic system. It may also be partially or totally integrated
with the power management circuit 106 in some applications.
[0022] Turning to FIG. 2, an exemplary block diagram of power
management circuitry 106 is depicted. As used in any embodiment
herein, "circuitry" may comprise, for example, singly or in any
combination, hardwired circuitry, programmable circuitry, state
machine circuitry, and/or firmware that stores instructions
executed by programmable circuitry. Power management circuitry 106
may comprise discrete components, or may be embodied as an
integrated circuit. "Integrated circuit", as used in any embodiment
herein, may mean a semiconductor device and/or microelectronic
device, such as, for example, a semiconductor integrated circuit
chip. In FIG. 2, certain portions of the system 100 depicted in
FIG. 1 have been omitted for clarity (for multiple power supplies
and batteries), but it is to be understood that like parts of FIG.
2 can be implemented in a manner consistent with an embodiment
depicted in FIG. 1, or alternatively in other system
implementations, without departing from this embodiment.
[0023] Power management circuitry 106 (and/or system 100) may also
comprise memory (not shown). Memory may comprise one or more of the
following types of memories: semiconductor firmware memory,
programmable memory, non-volatile memory, read only memory,
electrically programmable memory, random access memory, flash
memory, magnetic disk memory, and/or optical disk memory. Either
additionally or alternatively, memory may comprise other and/or
later-developed types of computer-readable memory. Machine-readable
firmware program instructions and/or operation parameters may be
stored in memory. As described below, these instructions and/or
operational parameters may be accessed and executed by power
management circuitry 106 generally to perform operations as may be
described herein.
[0024] As an overview, power management circuitry 106 may be
capable of, at least in part, selecting at least one power supply
among a plurality of different power supplies and coupling at least
one selected power supply to a load. Power management circuitry 106
may also be capable of charging at least one rechargeable battery
using at least one available power supply. In exemplary embodiments
described herein, power management circuitry 106 may also be
capable selecting at least one power supply among a plurality of
different power supplies and coupling at least one available power
supply to a load and at least one rechargeable battery. Power
management circuitry 106 may also be capable of selecting a
charging mode, among a plurality of charging modes, to charge a
rechargeable battery, and/or selecting a charging phase, among a
plurality of charging phases, to charge a rechargeable battery.
[0025] Power management circuitry 106 may comprise a plurality of
power paths 202, 204, 212, charger controller circuitry 206, and
power source selector circuitry 208. As will be detailed below,
power source selector circuitry 208 may be capable of controlling
the conduction state of one or more power paths 202, 204, and/or
212 to deliver power to the load 110, to one or more rechargeable
batteries 108, or both. Power path A 202 may conduct power to the
system load 110 and/or to the charger path 210 (via node 109) when
one or more high power supplies 102 is available. Power path A 202
may be turned off when one or more high power supplies 102 are OFF
(unavailable) to prevent reverse current flowing into the high
power supply 102.
[0026] Similarly, power path B 204 may conduct power to the system
load 110 and to the Charger path 210 via node 109 when one or more
restricted power supplies 104 are present. Restrictions associated
with power supply 104 may be stored in memory in power source
selector 208. As an example, one restriction may be that the total
current drawn out of the restricted power supply 104 is below a
preset maximum value. Power path B 204 may also perform a
soft-start procedure to prevent inrush current event when power
supply 104 is plugged in. Power path B 204 may be turned off to
prevent current flowing into the restricted power supply 104 when
it is not present, not ON, not approved to be used, or the high
power supply 102 is also present. During the on state of power path
B 204, if the total current, drawn by the system load 110 and the
rechargeable battery 108 exceeds the limit of the restricted power
supply 104, or any other restriction is violated (or new
restriction is imposed), power path B 204 may be switched off
immediately to protect the restricted power supply 104.
[0027] If power path B 204 is switched off, power path C 212 may be
turned on to continue powering the system load 110 and to keep the
power integrity on the system power line 109. If neither the high
power supply 102 nor the restricted power supply 104 is present, or
when the high power supply 102 is not present, and the Power path B
204 is turned OFF for any reason, the system load 110 may be
powered by the battery 108 through the conducting power path C 212.
Capacitor 220 could be used to maintain the power integrity on the
system power line 109 during the switching procedure from one power
supply to another.
[0028] Resistors 218 and 216 may be used to sense the current of
the high power supply 102 or the restricted power supply 104. When
the high power supply 102 is powering the system, power path B 204
may be off, and there may be no current flowing through resistor
216. Thus, the voltages at node 213 and node 215 may be
approximately equal, and the voltage drop between node 215 and node
109 may be approximately equal to the total current flowing out of
the high power supply 102 times the resistance of resistor 218.
When one or more restricted power supplies 104 are powering the
system, power path A 202 may be off with no current flowing through
it, so the voltage drop between node 215 and node 109 may be
approximately equal to the total current flowing out of the
restricted power supply 104 times the total resistances of resistor
218 and 216. In other words, in any case, the voltage drop between
node 215 and node 109 may be proportional to the corresponding
input current of either the high power supply 102 or the restricted
power supply 104. It is to be understood that other current sensing
devices may be used instead of resistors, for example, Hall
sensors, solid state sensors, and/or integrated sensors into the
corresponding power path.
[0029] The battery may be charged from one or more high power
supplies 102 and/or one or more restricted power supplies 104, via
charger path 207. The charging current flows from node 109 into the
charge path 207, and then flows out to node 207. Charger path 207
may be controlled by a control signal generated by charger
controller 206, at node 209. As will be detailed below, the control
signal may include a periodic on/off signal for switch mode
charging of a rechargeable battery, and/or an analog signal for
linear mode charging of a rechargeable battery. Resistor 214 may be
used to sense the charging current into the battery 108. It is to
be understood that other current sensing devices may be used
instead of resistors, for example, Hall sensors, solid state
sensors, and/or integrated sensors and/or other types of sensors
that may be considered equivalent.
[0030] Charger controller 206 may be capable of determining the
availability of at least one power supply and coupling, at least in
part, at least one available power supply to a rechargeable
battery. To that end, charger controller circuitry 206 may be
capable of receiving the input current information via node 215 and
node 109, the charging current information via node 207 and node
107, and the battery voltage information via node 107. In response
to one or more of these inputs, charger controller circuitry 206
may be capable of generating charging control signal (at node 209)
which may operate to couple a rechargeable battery to at least one
available power supply, in a manner which will be described in
detail below. Charger controller circuitry may also be capable of
communicating commands and data to power source selector circuitry
208, via communication link 217.
[0031] Power source selector circuitry 208 may be capable of
determining which power source should be used to power the system
load 110. For example, circuitry 208 may receive the information of
the three kinds of power sources at node 103, node 105 and node 107
respectively, and the corresponding current information from the
charger controller circuitry 206 (via link 217). In response
thereto, circuitry 208 may generate control signals at node 203,
node 205 and node 211 to control the conduction state (i.e., ON or
OFF) of power paths A 202, B 204 and C 212, respectively.
[0032] The schematic representation of one set of embodiments of
the three types of power paths according to the present invention
is shown in FIG. 3. Power path A 202 may comprise of a resistor 302
between node 103 and node 313, a voltage controlled switch 304
between node 103 and node 313, and a diode 306 with its anode
connected to node 313 and cathode connected to node 213. Diode 306
may prevent the reverse current flowing from the system into the
high power supply 102, and it may be a general semiconductor diode,
or a Schottky diode with reduced forward voltage drop, or any other
devices configured to have a typical characteristic of a diode.
Resistor 302 may provide a weak conducting path from the node 103
to the system via diode 306 to power the whole system up, and its
resistance sets a safe current limit for the high power supply 102
at the very beginning time of its plug-in. Voltage controlled
switch 304 is in parallel with resistor 302, and it receives a
controlling signal at node 203 to provide a very high resistance
path in off state and a very low resistance path in on state from
node 103 to node 313.
[0033] Power path B 204 may comprise of a resistor 308 between node
105 and node 315, a voltage controlled switch 310 between node 105
and node 315, a capacitor 312 between node 205 and node 315, and a
diode 314 with its anode connected to node 315 and cathode
connected to node 215. Diode 314 may prevent the reverse current
flowing from the system into the restricted power supply 104, and
it may be a general semiconductor diode, or a Schottky diode with
reduced forward voltage drop, or any other devices configured to
have a typical characteristic of a diode. Resistor 308 may provide
a weak conducting path from node 105 to the system via diode 314 to
power the whole system up, and its resistance sets a safe current
limit for the restricted power supply 104 at the very beginning
time of its plug-in. Voltage controller switch 310 is in parallel
with resistor 308, and it receives a controlling signal at node
205, which controls its own resistance to limit the current from
the restricted power supply during the transient, and to provide a
very high resistance path in off state and a very low resistance
path in fully on state from node 105 to node 315. Capacitor 312
could be used if necessary to guarantee the slow change of the
voltage at node 205 in the soft-start procedure and to keep the
power integrity when the power is switched from battery to this
restricted power supply 104. In some cases, an additional capacitor
can be connected between node 105 and node 205 for better
performance.
[0034] Power path C 212 may comprise of a voltage controlled switch
318 between node 109 and node 107, and a diode 316 with its anode
connected to node 109 and cathode connected to node 107. Diode 316
may be a general semiconductor diode, or a Schottky diode with
reduced forward voltage drop, or any other devices configured to
have a typical characteristic of a diode. If neither the high power
supply 102, nor the restricted power supply 104 is available, the
switch 318 should be on, and the system load 110 is powered by the
battery 108 through switch 318. During the transitions from battery
to restricted power supply, the aforementioned switches are driven
following the Brake-Before-Make (BBM) or Make-Before-Brake (MBB)
procedures. If the battery voltage is higher than a predetermined
value when the transition is initiated, the BBM procedure should be
used; the switch 318 should be made off right away, and the switch
310 driven gradually to limit the current through it before being
made fully ON to prevent an abnormal charging current into the
battery 108; the system load 110 should be powered by the battery
108 through the conducting diode 316 until the restricted power
supply take on it the load. If the battery voltage is lower than
the limit, the MBB procedure have to be used; the switch 318
remains ON until the restricted power supply is fully connected
through the ON switch 310, assuring the system power integrity. In
this case a limited current will reach the battery, but charging
integrity may be maintained since the battery voltage may be far
below its maximum limit.
[0035] Charger path 210 may be used to conduct the charging current
from the system line 109 to node 207, then through resistor 214
into the battery 108. In at least one embodiment, the charger
circuitry 206 may select at least one charging mode, among a
plurality of charging modes, to charge a rechargeable battery 108.
In an exemplary embodiment, charger circuitry may select between a
switch mode and linear mode. Accordingly, charger path 210 may
comprise different circuitry, depending on the operating mode of
the charger circuitry 208. The schematic representation of
exemplary embodiments of the charger path 210 is shown in FIG. 4,
where 210A may include an asynchronous buck converter type charger
for switch mode, 210B may include a synchronous buck converter type
charger for switch mode, and 210C may include a variable resistor
type charger for linear mode.
[0036] In the asynchronous buck 201A, a switch 402 controlled by
node 209, may be connected between node 109 and node 403. A diode
404 may be connected between node 403 and ground, with its positive
terminal tied to ground. An inductor 406 may be connected between
node 403 and node 207, and a capacitor 408 may be connected between
node 207 and ground. In the operation, switch 402 is periodically
switched on/off, as controlled by controller 206 via control signal
at node 209, thereby generating switch mode power to one or more
rechargeable batteries 108.
[0037] In the synchronous buck 2101B, a switch 412 controlled by
node 209A, may connected between node 109 and node 413. Another
switch 414 controlled by node 209B, may be connected between node
412 and ground. An inductor 416 may be connected between node 413
and node 207, and a capacitor 418 may be connected between node 207
and ground. During normal charging of the battery 108, switch 412
and switch 414 may be controlled so that they are not on at the
same time. To that end, and in this embodiment, charger controller
206 may be capable of generating control signals at nodes 209A and
209B in a manner such that switches 412 and 414 do not conduct
simultaneously.
[0038] In the variable resistor type charger path 210C for the
linear mode, a variable resistor 422 may be connected between node
109 and node 207. The resistance of the variable resistor 422 may
be controlled by a control signal generated by charger controller
circuitry 206 at node 209. A capacitor 428 may be connected between
node 207 and ground, although it is equally contemplated that in
this embodiment the capacitor 428 may be omitted. In operation, by
adjusting the resistance of the resistor 422, the amount of
charging current delivered to battery 108 may be controlled to
permit, for example, that battery to be charged while maintaining
current to the system load 110.
[0039] The variable resistor and the any of the switches described
herein may include the same type of devices, such as the bipolar
junction transistor (BJT), the isolated gate bipolar transistor
(IGBT), and the metal-oxide semiconductor field effect transistor
(MOSFET), or any other kind of controlled devices.
[0040] A schematic representation of one embodiment of charger
controller circuitry 206 is depicted in FIG. 5. A switch 502,
controlled by a control signal at node 503, and a resistor 504 may
be connected in series between the system power line 109 and node
207. A comparator 512 may be included to compare the battery
voltage at node 107 and a reference voltage V.sub.REF1, and may
also generate the control signal at node 503. If the battery
voltage is less than a set minimum voltage, switch 502 may be
closed by the control signal at node 503. This control signal may
also be used to turn pulse generator circuitry 520 and control
signal generator circuitry 522 OFF, and to pull voltage at node 515
to ground through the turned-on switch 528.
[0041] Referring again to FIG. 2, a "wake-up phase" may include a
situation in which the charging current flows from the system power
line 109 through charger controller 206 to node 207, then into the
battery 108 directly via the resistor 214. In the wake-up phase,
charging current (delivered through charging path 210) may be
determined by the resistance of the resistor 504 (FIG. 5).
[0042] Referring again to FIG. 5, in the constant current phase or
constant voltage phase, switches 502 and 528 may be off. The node
515 gets a constant current from the source 526, while OTA
(operational transconductance amplifier) circuitry 506, 508 and/or
510 may be sinking current from the same node. If the voltage
difference between node 215 and node 109, which may be proportional
to the input currents, reaches a predetermined value, OTA 506 may
operate to generate a current to discharge node 515. Otherwise the
internal discharging current source in OTA 506 may be disabled. The
signal at node 217 may be proportional to the input current, and it
may be sent to power source selector 208. If the voltage difference
between node 207 and node 107, which may be proportional to the
charging currents, reaches a predetermined value, OTA 508 may
operate to generate a current to discharge node 515. Otherwise the
internal discharging current source in OTA 508 may be disabled. If
the voltage at node 107, which may be the battery voltage or a
function of the battery voltage, reaches a predetermined value, OTA
510 may operate to generate a current to discharge node 515.
Otherwise the internal discharging current source in OTA 510 may be
disabled.
[0043] Saw tooth oscillator circuitry 518 and pulse generator
circuitry 520 may be used to generate a pulse signal at node 521,
and the pulse signal may have a selected duty cycle for switch mode
charging. The duty cycle may be determined by the comparison result
of the voltage at node 515 with the saw tooth signal at node 519.
The higher the voltage at node 515, the higher the duty cycle may
be. Here the duty cycle refers to the ratio between the time when
switch 402 or 412 is on and the total time of one period. When the
voltage at node 515 is less than a predetermined value V.sub.LIM1,
the duty cycle of the output pulse at node 521 may be approximately
zero, thus the charging current may be approximately zero.
[0044] Control signal generator circuitry 522 may be used to
generate an analog signal at node 523 for linear mode charging.
This signal at node 523 may be determined by the value of the
voltage at node 515, and may be used to adjust the resistance of
the variable resistor 422 and thus, the charging current. When the
voltage at node 515 is less than a predetermined value V.sub.LIM2,
the output signal on node 521 may operate to set the resistance of
the variable resistor 422 to an extremely large value, thus the
charging current may be approximately zero.
[0045] When the charger is in wake-up phase, the voltage at node
515 may be discharged to ground. If it is required to charge the
battery in a constant current or a constant voltage phase, the
voltage at node 515 may be charged up gradually from zero due to
the finite charging time of capacitor 516. The charging current may
stay near zero until the voltage at node 515 is higher than
V.sub.LIM1 or V.sub.LIM2, and the charging current may increase
slowly to the target value (this may be true even the voltage at
node 515 is higher than V.sub.LIM1 or V.sub.LIM2.) This soft-start
charging procedure may operate to prevent inrush charging current
into the battery, and may protect the battery from damage.
[0046] The resistor 514 and the capacitor 516 may used to keep the
feedback loop stable, and the resistance and capacitance may differ
for the switch mode and linear mode.
[0047] A "constant current charging phase" may include the
condition when the charging current reaches its predetermined
maximum value and OTA 508 may determine and stabilize the voltage
at node 515. If the system load needs more current, and the total
input current reaches its preset value, OTA 506 may cause the
voltage at node 515 to decrease, thus the charging current may be
adjusted automatically to its maximum permitted value. When the
battery voltage reaches the target value, charging may be
accomplished using a "constant voltage phase". During a constant
voltage phase, in order to prevent over-voltage of the battery, OTA
510 may cause the voltage at node 515 to decrease. The charging
current may adjusted automatically at its maximum permitted maximum
value to keep battery voltage stabilized at its target value.
[0048] Switch 524 may couple the appropriate signal to node 209 to
control the charger path 210. For example, for switching mode
charging, the signal at node 521 may be coupled to node 209, while
for linear mode charging, the signal at node 523 may be coupled to
node 209.
[0049] An exemplary schematic of one embodiment of the power mode
selector circuitry 208 is depicted in FIG. 6. Selector 208 may
include a presence detector 624, which may receive one or more
signals at node 103 from the high power supply 102, and may
determine whether if a high power supply 102 is present or not
and/or has the expected characteristics or not. If the high power
supply 102 is present, the signal on node 203 may turn power path A
202 on. The signal on node 203 may also be connected to the logic
block 620, which may receive information about the other power
supplies (e.g., 104), and based on this information block 620 may
generate a signal to control conduction state of power path C 212.
A presence indication signal at node 203 may cause the signal at
node 211 to block power path C 212. The signal at node 203 may also
be coupled to logic cell 616, which may control the output of the
node 617.
[0050] Comparator 622 may compare the battery voltage at node 107
with a predetermined value V.sub.REF2 and may also provide an
indication signal at node 623. Presence detector 614 may sense the
restricted power supply 104 at node 105, and may provide a presence
indication signal of the restricted power supply 104 at node 615.
Comparator 610 may compare the signal at node 217, which may be
proportional to the input current, with a predetermined value
V.sub.REF3 to generate a signal at node 627 indicating if the input
current is over a predetermined limit.
[0051] Logic cell 616 may operate to drive the node 617 based on
the input current status signal at node 627, the presence status
signal of the restricted power supply 104 at node 615, and the
presence status signal of the high power supply 102 at node 203. If
the high power supply 102 is not present, and the restricted power
supply 104 is present, and no restriction related to power supply
104 is violated, the logic cell 616 may provide a signal at node
617 indicating that the restricted power supply 104 can be used.
This may operate to drive switches 606 and 612 out of
synchronization. Switches 606 and 612 may operate to make node 205
fast ramping to high, or ramping down with a controlled slope to
control, so that path B 204 moves from a quickly off conduction
state to smoothly ON conduction state. This signal (node 617) may
also be sent to the timer 618 which may set a transition time for
path B. Since the default state of the switch 604 may be on, at the
beginning of the restricted power supply 104 plug-in, its input
current may limited by resistor 308 at a lower value than the
maximum rating current of the power supply 104. The amplifier OTA
602 in conjunction with the current source 608 may drive node 205,
which is the driving signal of the Restricted Power Supply path B
204, to decrease slowly to the equivalent resistance of the path B
204. The current delivered from the restricted power supply 104 and
the indicative signal 217 may start to increase. When the input
current reaches a limit value set by V.sub.REF1, OTA 602 may
operate to inject more current into node 205, actively stabilizing
the resistance of the path 204, thus limiting the current. After a
time period defined by timer 618 (which may be defined as
sufficient to allow the system to settle), the signal at node 619
may turn switch 604 off, and the discharging current of current
source 608 may eventually pull the voltage at node 205 to ground,
turning the switch 310 fully on.
[0052] Logic block 620 may generate a control signal at node 211 to
control the conduction state of power path C 212. To assure power
integrity during a switch among different power inputs, the signal
at node 211 may turn switch 3180N to make the battery ready for
powering the system load 110 if neither the high power supply 102
nor the restricted power supply 104 is present, as indicated by the
signals at nodes 203 and 615 respectively.
[0053] If high power supply 102 is not present, as indicated by the
signal at node 203, and the restricted power supply 104 is present,
as indicated by the signal at node 615, and the battery voltage at
node 107 is less than the threshold voltage V.sub.REF2 as indicated
by the signal at node 623, and it is in the soft-start procedure as
indicated by the signal at node 619, in this case, there may be a
limited charging current flowing into the battery through the
conducting switch 318. Since the battery voltage may be smaller
than V.sub.REF2, and V.sub.REF2 may be smaller than the maximum
voltage of the battery, this charging current may be within
acceptable safety limits for the battery.
[0054] If high power supply 102 is not present, as indicated by the
signal at node 203, and the restricted power supply 104 is present,
as indicated by the signal at node 615, and an over-current event
for the restricted power supply 104 occurs, as indicated by the
signal at node 627, the power source selector 208 may operate as
follows: if the battery voltage is larger than V.sub.REF2 during
the soft-start procedure of the restricted power supply 104, switch
318 may be turned off immediately by the signal at node 211 to
prevent an abnormal over-charging current. At this time the system
load may be powered from the battery via the forward conducting
diode 316.
[0055] FIG. 7 depicts a flowchart 700 of exemplary operations which
may be performed according to an embodiment. Operations may include
selecting at least one power supply, among a plurality of different
power supplies, and coupling at least one available power supply to
a load 702. Operations may also include selecting at least one
charging mode, among a plurality of different charging modes, to
charge a rechargeable battery 704.
[0056] Thus, in summary, an apparatus embodiment provided herein
may include an integrated circuit that may be capable of selecting
at least one power supply, among a plurality of different power
supplies, and coupling at least one available power supply to a
load. The integrated circuit may also be capable of selecting at
least one charging mode, among a plurality of different charging
modes, to charge a rechargeable battery.
[0057] Advantageously, the embodiments described herein may provide
high performance power management for an electronic device.
Moreover, certain embodiment described herein may be capable of
receiving power from high power supplies, restricted power
supplies, and/or batteries. Other advantages may include powering
the system load and charging the battery at the same time. In
exemplary embodiment, the integrated circuit can provide two
charging modes: switch mode and linear mode. The integrated circuit
may also provide, for example, three different charging phases:
wake-up phase, constant current phase, and constant voltage phase.
The charging current can be adjusted automatically to firstly
fulfill the system requirement, and allocating all remaining
available power to charge the battery in order to provide a fast
battery charging time. Further, the integrated circuit may be
capable of selecting power inputs automatically according to their
status to ensure safety of the power supplies, the system load
and/or one or more rechargeable batteries.
[0058] The terms and expressions which have been employed herein
are used as terms of description and not of limitation, and there
is no intention, in the use of such terms and expressions, of
excluding any equivalents of the features shown and described (or
portions thereof), and it is recognized that various modifications
are possible within the scope of the claims. Accordingly, the
claims are intended to cover all such equivalents.
* * * * *